Spring is perfect time to tap the maple

It's a sticky situation, to say the least. You want to be kind to a tree, yet you want to steal its very lifeblood.

It's maple sugaring time.

March is the best month for tapping sugar maple trees and Kunso Kim, the Morton Arboretum's head of collections, says sap collection will not harm the tree if done properly.

"A limited amount of sap is taken," he said, "and at this time of year, sap is flowing heavily in the tree."

Like all trees, maples produce a sugar-like substance as part of photosynthesis.

"Sugar maples tend to have more sugary content than other trees," Kim said.

In addition to sugar maples, lack maples and occasionally red maples are sometimes tapped in the United States. Box elder, those weedy trees that are members of the maple family, also produce a weak syrup. In other countries, Korea, for example, maples like the painted maple are tapped for their sap.

Tapping maple trees is usually done in late winter or early spring with nighttime temperatures of about 20 degrees Fahrenheit and sunny days of about 40 degrees. These temperature swings help force the sap to flow more freely. Typically, if you wait until the end of March, with warmer temperatures, the tree begins its annual growth and the sap produced will be more bitter.

Sap flows heavily for only about three to four weeks. Only healthy trees of about 18 inches or more in diameter should be tapped. The tapping hole should be drilled about three to four feet from the ground, and about one to two inches deep into the tree. A spout is inserted into the tap hole and sap drips from that into a collection bucket below. After collection, the sap is boiled down to increase the sugar concentration.

A typical tree-tapping may produce about 10 gallons of sap in a season - just enough to make about one quart of maple syrup. Commercial producers may grow acres of trees for economy's sake, but a home hobbyist might enjoy the experience with just one tree.

If you're counting calories or otherwise want to forego the sugaring process, don't overlook the subtle flowers and foliage on maples in the springtime.

"Normally, you don't grow maples for flowers," Kim says. "But red maples' flowers can be striking."

Red maples tend to produce clusters of small, reddish flowers before leafing out. The clusters are beautiful against the bare branches in spring.

Kim also likes Japanese maples in the spring.

"Some are really striking when they start to leaf out," he says. The foliage is particularly interesting as it emerges, revealing a unique texture and pattern unlike its late-summer look.

Of course, spring is a great time to plant maples in anticipation of their renowned autumn color. In addition to sugar maples, Kim's favorites include the lesser-known paperbark maple (Acer griseum) and three-flower maple (Acer triflorum). While not as showy as sugar maples in the fall, paperbark and three-flower maples have interesting exfoliating bark, and often are grown as multi-stemmed trees. Their smaller size makes them suitable for most home gardens.

Manchurian striped maple (Acer tegmentosum) and snake bark maple (Acer davidii) both have uniquely striated bark and are also sized nicely for smaller yards. They not only require less sun than the showy sugar maples, but also don't cast as much shade themselves.

Whether you're ready to tap maples for their sugar or for their ornamental qualities, spring is a great time to consider maples in your yard.

• Cathy Maloney is a writer for the Morton Arboretum in Lisle. Her column appears monthly in Neighbor.